What's the cause of all this freak weather?

Hurricane Charley battered the Florida coast earlier this month, causing millions of pounds worth of damage and leaving 19 people dead. Closer to home, a 10ft wall of water caused havoc in the Cornish village of Boscastle as mother nature unleashed her fury.

Meanwhile, in Scotland a main road was turned into a river of mud as a landslide struck due to heavy rain, and in France, Bangladesh and India freak weather also caused havoc and disaster.

Now UK forecasters are predicting an even wetter end to August, with more torrential rain and gales sweeping across Britain and warnings of further flash flooding. Some farmers could now face financial difficulties due to ruined crops and many householders, businesses and motorists have suffered problems caused by the downpours.

Related insurance claims have increased fourfold in recent weeks, according to some reports, and the cost of the clean-up operation in Boscastle alone has been put at around £25 million

The basic cause of the bad weather in the UK has been a low pressure system combining with warm summer air. This has led to an unusually large amount of moisture being carried up into the atmosphere. Hurricanes on the western Atlantic have also been feeding into the weather systems affecting Britain.

However, coming only 12 months after Britain recorded its highest temperature ever, the freak conditions have inevitably led to more speculation about the long-term cause.

Experts remain divided as to what is causing the extreme weather conditions. Some blame global warming for the floods and storms, while others point to local factors, such as topography.

Short memories

Weather expert Dr Mark Saunders from University College, London, cautioned against blaming global warming. He said: "It is not unusual for one to get extreme weather some place in the world. There is no evidence that extreme weather is becoming more common in terms of storms or flooding.

"We have seen similar incidents in the UK over the last 30 to 50 years. It is just natural climatic variability."

He added: "It seems we have short memories in this country. If you go back over the years there have been similar incidents, however there is no evidence that severe storms are becoming more frequent. In Cornwall (Boscastle), it was local factors that contributed to the flooding. One hundred miles away there was nothing unusual at all."

Dr Saunders said in recent years meteorologists had witnessed a downward trend in the number of hurricanes battering Florida and other US states.

However, he said experts were now more confident that global temperatures had risen as a consequence of the greenhouse effect. Indeed, there seems little doubt that the world is getting hotter. Eight of the warmest years ever recorded have occurred since 1990.

Ice sheets, meanwhile, have decreased along with global snow cover as the world experiences the most rapid rise in temperatures since the end of the ice age.

Despite this, Barbara Young, chief executive of the Environment Agency, insisted it was still too early to blame the extreme weather on global warming.

"We're certainly seeing some extreme weather around the world, but we can't really say at the moment if this is down to climate change," she said. "But the hotter summers interspersed with thunderstorms, along with milder winters are the kind of conditions experts have predicted would happen more often once climate change kicked in."

If extreme weather does become more common, it will make it increasingly difficult for the Environment Agency to predict and guard against, according to Mrs Young. "At the end of the day when you have extreme events like Boscastle there's very little we can do," she commented.

Unless greenhouse gases are dramatically cut, experts predict that by the end of the century, average temperatures in the UK could rise by between two and five degrees Celsius.

Getting warmer

Climate models predict that, by 2080, the south east of England will be three times more likely to experience extremely warm temperatures like those of last summer. And with such temperatures becoming more common, a freak summer of the future could see temperatures hitting the mid-40s.

Average summer rainfall in the UK, meanwhile, is expected to drop by up to 60% by 2080, with the sharpest decline expected in the already water-stressed south east. Soil moisture, meanwhile is expected to fall by up to 50%.

However, hot summers will lead to more thunderstorms, and as the rain drops on dry ground the kind of flash flooding seen recently in Northern Ireland could become more common.

"Unless we do cut emissions then we can get used to the kind of extreme weather we've been seeing over the last few years,'' Mrs Young warned.

Met Office forecaster Clive Burlton said that while specific events such as the disaster at Boscastle, Cornwall, or the landslide near Stirling, Scotland, could not be linked directly to global climate change, it was likely such events would become more common.

"The expectation is that there are going to be more heatwaves and more extreme events. These sort of events are expected to increase and there will be more extremes than in the past," he said.

Dangerous threat

The European Environment Agency has also issued a stark warning about the future of our weather.

The agency said in a report this week that the world could see floods, storms, droughts and other extreme weather becoming more common in years to come.

Prof Jacqueline McGlade, European Environment Agency Executive Director, said: "This report pulls together a wealth of evidence that climate change is already happening and having widespread impacts, many of them with substantial economic costs on people and ecosystems across Europe."

Throughout the 1990s, the EEA has been "detecting increasing global warming," she said. "What is new is the speed of change."

Serious flooding in 11 countries in August 2002 killed about 80 people and caused economic losses of at least 15 billion euros (£10 billion). The year after, a heatwave in western and southern Europe was responsible for more than 20,000 excess deaths, particularly among elderly people. The EEA added that northern Europe would see wetter conditions while the south was likely to become drier.

Friends of the Earth campaigns director Mike Childs warned: "The consequences of climate change are a very real and dangerous threat, yet international leaders seem to pay little heed to the warning bells.

"The Prime Minister must convince his fellow world leaders that climate change is as big a threat to people and the planet as international terrorism."